Mental and behavioral health during adolescence is an area of critical public health concern because morbidity and mortality rates increase 200-300% from childhood to late adolescence. A major dimension of these serious health problems is related to difficulties with the control of emotions. In order to understand how challenges to emotion regulation during adolescence contribute to specific health problems, researchers need better tools for measuring emotional reactivity and regulation during this developmental period. This project applies a developmentally informed social affective neuroscience perspective to the development of a new "toolbox" for studying emotional reactivity and regulation in adolescence. This requires an integration of the fields of developmental psychopathology, social neuroscience, and affective neuroscience. Combining key elements of these disciplines will facilitate the development of tools grounded in neuroscience that also have broader developmental, clinical, and social relevance. Because of the importance of the social sphere in adolescence, we focus on socially relevant paradigms that will facilitate an understanding of how social influences (e.g. parents, peers, media) contribute to adolescents'emotionality, and how neurobiological substrates underlie social and emotional processes. Specifically, we will develop and refine 3 sets of tools: (a) laboratory pupillary and functional magnetic resonance imaging (fMRI) social-emotional information processing tasks;(b) behavioral observation of parent-child affective interactions with concurrent pupillary data;and (c) a cell-phone based Ecological Momentary Assessment (EMA) protocol measuring adolescents'emotional reactivity and regulation in natural social contexts. Our aims are to (1) develop and establish initial psychometric properties for these measures, (2) integrate these measurement approaches across levels of context and time, and (3) examine the validity of these approaches in discriminating clinical groups and detecting developmental/pubertal differences in emotional reactivity and regulation. As first steps, we will focus specifically on the utility of these methods in research on adolescent depression--a common and debilitating adolescent health problem associated with chronic and recurrent impairment into adulthood. Innovative aspects of this work include the development of new methodologies for sampling "real-world" phenomena, integration of neuroscience with the social environment by developing laboratory paradigms that tap social processes, and improvements in the assessment of co-occurring social and biological processes through the development of mood inductions and peer and parent-child interaction tasks that can be used to collect concurrent neurobiological, behavioral and observational data. Ultimately, these tools could be useful for investigators examining a wide range of adolescent health problems across disciplines, including researchers in the areas of high risk research, treatment and prevention, longitudinal developmental research, psychology, neuroscience, and behavioral medicine. Developing new biological and ecological tools for measuring emotional reactivity and regulation is relevant to the missions of NICHD, NIMH, NIDA, and NIAAA in that emotion regulation has been identified as a critical yet poorly understood domain in normative child and adolescent development and in the development of problems in mental health, drug and alcohol abuse, and risk-taking and reckless behavior that leads to a broad range of health consequences. Developing tools that can facilitate a better understanding of the mechanisms through which emotional reactivity and regulation contribute to adolescent health is critical because it could lead to improvements or adaptations of existing prevention and intervention programs, the development of new prevention and intervention programs based on new scientific discoveries, and better matching of patients to specific treatment protocols based on emotional profiles. Tools that can identify initial disruptions in emotion regulation and facilitate early intervention during this period of relative plasticity could lead to long-term reductions in health-related cost and suffering in adulthood.